export default `
uniform sampler2D texture;    
varying float brightness;    
varying vec2 vUV;    
    
// Normalizes a value between 0 - 1    
float normFloat(float n, float minVal, float maxVal){    
    return max(0.0, min(1.0, (n-minVal) / (maxVal-minVal)));    
}    
    
void main() {    
    // Additive    
    // gl_FragColor = texture2D( texture, vUV) * brightness;    
    
    // Subtractive    
    // gl_FragColor = texture2D( texture, gl_PointCoord ) - vec4( color, 1.0 );    
    // gl_FragColor *= opacity;    
    
    // Multip    
    /* gl_FragColor = -texture2D( texture, gl_PointCoord ) * opacity;    
    gl_FragColor *= 1.0 - vec4( color, 1.0 );    
    gl_FragColor += 1.0; */    
}
`